Method for mapping quality of service requirements to radio protocol parameters

ABSTRACT

An apparatus and method for transmitting packets having quality of service requirement wherein the quality of service requirements associated with the packets are received at an input, said quality of service parameters include at least one of delay, bandwidth, peak bandwidth and retransmission bandwidth. The received quality of service parameters are mapped to radio protocol parameters including at least one of a priority slot interval, a priority slot phase, a packet duration and modulation format for the radio channel. The packets are transmitted on a radio channel according to the mapped radio protocol parameters.

RELATED APPLICATION(S)

This application claims priority from and incorporates herein byreference the entire, disclosure of U.S. Provisional Application Ser.No. 60/313,329 filed Aug. 17, 2001.

TECHNICAL FIELD

The present invention relates to quality of service within ad hoc radiochannels of a data communications system, and more particularly, to amethod for mapping quality of service parameters to a set of radioparameters suitable for use with a token based multiple access radiocontrol protocol for a time-slotted channel.

BACKGROUND OF THE INVENTION

In the last decade, progress in radio and VLSI technology has fosteredthe widespread use of radio communications in consumer applications.Portable devices such as mobile radios, PDAs, pagers, and mobilecomputers can now be produced having acceptable cost, size and powerconsumption. Radio communication systems for personal usage differ fromradio systems like the public mobile phone network because they operatein an uncoordinated environment. These radio communications systemsrequire an unlicensed band enabling personal devices to work anywhere inthe world with a suitable system capacity. One radio band meeting thisrequirement is the ISM (Industrial, Scientific and Medical) band at 2.4GHz, which is globally available. The band provides 83.5 MHz of radiospectrum. One example of a short range radio technology particularlysuited for personal applications within the ISM band is the Bluetoothwireless technology. Bluetooth provides an air interface designed foroperation in the ISM band and lends itself to providing low cost, lowpower implementations for radio. Using the Bluetooth wirelesstechnology, personal devices may be connected in an ad hoc fashion.

As technologies like Bluetooth become widely deployed, the possibilityof different types/classes of applications running from differentdevices attempting to share the same radio channel becomes highlylikely. The passing of unrelated traffic through a shared channel islikely to have a heavy influence on each traffic stream's delay, jitterand packet loss. Some types of traffic, for example, TCP connectionscarrying e-mail, tolerate latency better than they tolerate packet loss.However, other types of traffic, for example, streaming video or audio,prefer shorter delays over “no loss”. To enable co-existence of theseseemingly different types of services, the radio protocols are expectedto offer reasonable QoS guarantees. Thus, there is a need for amulti-service environment wherein traditional bursty traffic such asfile transfers, e-mails or web browsing may share the same radio channelas traffic with more rigorous latency, jitter and/or packet lossrequirements, such as voice. Thus, there is a need for a method formapping the general QoS parameters provided by an application into a setof radio-specific elements.

SUMMARY OF THE INVENTION

The present invention overcomes the foregoing and other problems with anapparatus and method for transmitting packets having quality of servicerequirements. The quality of service parameters associated with thepackets to be transmitted include at least one of delay, bandwidth, peakbandwidth and retransmission bandwidth are received at an input. Thequality of service parameters are mapped to radio protocol parameters ofthe radio channel. The radio protocol parameters include at least one ofa priority slot interval, a priority slot phase, a packet duration and amodulation format. The packets are transmitted on the radio channelaccording to the mapped radio protocol parameters.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the method and apparatus of the presentinvention may be obtained by reference to the following DetailedDescription when taken in conjunction with the accompanying Drawingswherein:

FIG. 1 illustrates an ad hoc network between a plurality of personaldevices communicating via one or more radio channels;

FIG. 2 illustrates the operation of a Ping-Pong protocol scheme;

FIG. 3 illustrates a use of priority slots providing unconditionalaccess to a radio channel within the Ping-Pong protocol;

FIG. 4 is a block diagram of a mapping function according to the presentinvention;

FIG. 5 illustrates the assignment of a priority slot interval for asingle time critical service;

FIGS. 6 a and 6 b illustrate the use of differing modulation formats;

FIG. 7 illustrates the quality of service parameters associated withasynchronous services;

FIGS. 8 a and 8 b illustrate the mapping of services requiringretransmission bandwidth;

FIG. 9 illustrates the staggering of two isochronous services withidentical quality of service requirements sharing a same channel;

FIG. 10 illustrates the mapping of radio protocol parameters forsynchronous and isochronous services sharing a same channel;

FIG. 11 illustrates the sharing of a channel between synchronousservices, isochronous services and best effort services;

FIG. 12 illustrates the sharing of a same radio channel by time-criticaland asynchronous services; and

FIG. 13 illustrates contention problems on a radio channel.

DETAILED DESCRIPTION

Merging of internet and mobile applications has made it possible for theuser of mobile/portable devices to access both internet and telecomresources. The provision of the end-to-end service may be conveyed overseveral networks and realized by the interaction of the protocol layersinvolved. To provide end-to-end QoS, all the interacting protocol layersmust be QoS enabled. With the emergence of short range wirelesstechnologies like Bluetooth, the last link can increasingly be expectedto be radio based. Accordingly, QoS support must also be provided here.

Referring now to the drawings, and more particular to FIG. 1, there isillustrated an ad hoc network 5. A plurality of personal devices 10 maycommunicate via a wireless link 15 using, for example, the Bluetoothwireless protocol. The Bluetooth wireless protocol will enable thepersonal devices 10 to communicate via the wireless links 15 in the ISMband. The wireless connections 15 will have various quality of service(QoS) requirements required by applications being executed by thepersonal device 10. The applications may be time critical or non timecritical. Time critical applications must transmit data within aspecific time period. Non time critical applications do not require datato be transmitted within any particular time period.

Referring now to FIG. 2, there is an illustration of a Ping-Pongprotocol used in the method of the present invention. A transmittedpacket can be regarded as carrying a token. As the packet is received,the sending unit implicitly gives the token to the receiving unit, whichenables the receiving unit to send a second packet. The unit with thetoken can then send a third packet to any other unit in the network. ThePing-Pong protocol enables a multiple access control (MAC) scheme. Whilethe illustration of FIG. 2 and the subsequent figures in many casesillustrate a separate trace associated with a particular transmittingunit or service, it should be realized that this is merely for purposesof illustration, and the communications are occurring upon the sameradio communications channel 25 having a number of time slots 30 definedtherein.

FIG. 2, illustrates an exemplary operation of a token ping-pong schemeamong three units in accordance with the present invention. Acommunication channel 200 permits communication among the unit 102(1),the unit 102(2), and unit 102(3). The channel 200 is divided into 24time-division-duplex slots similar to those illustrated in FIG. 1.Packets 201-210 are shown being transmitted on the channel 200. As wasillustrated in FIG. 1, transmission of packets begins at the boundary ofa slot and can continue for a variable length of time.

The unit 102(1) begins transmission of the packet 201 at the boundary ofthe slot 0. The packet 201, which is being transmitted to the unit102(2), occupies the entirety of the slot 0 and the slot 1 and part ofthe slot 2. Upon receipt of the packet 201, the unit 102(2) now has thetoken, and can transmit a packet beginning at the boundary of the slot3. In practice you must allow for RF switching time, we assume theswitching time to be zero. The unit 102(2) has a packet to transmit tothe unit 102(1), so, at the boundary of the slot 3, the unit 102(2)begins to transmit to the unit 102(1) the packet 202. The packet 202occupies the entirety of the slots 3-5 and part of the slot 6.

Following receipt of the packet 202, the unit 102(1) now has the token;therefore, at the boundary of the slot 7, the unit 102(1) can begin totransmit the packet 203, which is sent to the unit 102(2). The packet203 occupies only part of the slot 7. The unit 102(2), which now has thetoken, can begin to transmit the packet 204 at the boundary of the slot8. The packet 204 is transmitted to the unit 102(1) and occupies theentirety of the slot 8 and part of the slot 9.

Upon receipt of the packet 204, the unit 102(1) has the token and canbegin transmission of the packet 205, which is transmitted to the unit102(3) beginning at the boundary of the slot 10. The packet 205 occupiesthe entirety of the slots 10 and 11 and part of the slot 12. Followingreceipt of the packet 205, the unit 102(3) has the token. Therefore, theunit 102(3) can transmit the packet 206, which is transmitted to theunit 102(1), beginning at the boundary of the slot 13. The packet 206occupies the entirety of the slot 13 and part of the slot 14. Therefore,the unit 102(1), upon receipt of the packet 206, can transmit a packetbeginning at the boundary of the slot 15.

The unit 102(1) transmits the packet 207 to the unit 102(3) beginning atthe boundary of the slot 15. The packet 207 occupies the entirety of theslot 15 and part of the slot 16. Upon receipt of the packet 207 by theunit 102(3), the unit 102(3) has the token and can transmit a packetbeginning at the boundary of the slot 17. At the beginning of the slot17, the unit 102(3) transmits the packet 208 to the unit 102(2). Thepacket 208 occupies the entirety of the slot 17 and a portion of theslot 18. Therefore, the unit 102(2) has the token and can begintransmitting a packet beginning at the boundary of the slot 19.

At the beginning of the slot 19, the unit 102(2) transmits to the unit102(1) the packet 209. The packet 209 occupies the entirety of the slots19 and 20 and part of the slot 21. Upon receipt of the packet 209, theunit 102(1) receives the token and can begin transmitting a packet atthe boundary of the slot 22. The unit 102(1) begins transmitting thepacket 210 at the boundary of the slot 22. The packet 210 occupies theentirety of the slot 22 and part of the slot 23. Upon receipt of thepacket 210, the unit 102(2) has the token and can begin transmission ofa packet at the boundary of the slot 24 (not shown).

Thus, FIG. 2 illustrates that, upon receipt of a packet, a unit receivesthe token and is permitted to transmit a packet to any other unitbeginning at the boundary of the next slot following its receipt of apacket. Packets can be variable in length and thus can occupy a variablenumber of slots. The Ping-Pong protocol is more fully described inprovisional application 60/226,965, filed Aug. 22, 2000; U.S.application Ser. No. 09/710,204, filed Nov. 9, 2000 which areincorporated herein by reference. The Ping-Pong protocol illustrated inFIG. 2 does not provide any guarantees in terms of granting access tothe channel. In order to guarantee access to a channel, the tokenpassing mechanism may be extended to provide unconditional access to thechannel 200 at selected times.

Referring now to FIG. 3, there is illustrated a method for achievingunconditional access by using a priority slot 360. In FIG. 3, Unit C hasa priority slot 360 at a fixed interval of eight time slots. At thepriority slot 360, Unit C obtains an exclusive right to transmit datapackets 365 on a channel. This occurs whether or not the token hasactually been given to Unit C by previous packet reception from eitherUnit A or Unit B. The token is granted to Unit C based upon ownership ofthe priority slot 360 at a fixed point in time.

The Ping-Pong protocol and the priority slot 360 constitute a multipleaccess control (MAC) mechanism on the radio channel 200 that can be usedto provide quality of service (QoS) to applications within personaldevices 10. The goal in a QoS enabled environment is to enablepredictable delivery for certain types of traffic, regardless of whatother traffic is flowing through the network 5 at any given time.

From an application point of view, quality of services is characterizedby placing requirements on one or more of the following parameters:bandwidth, comprising user information that needs to be transmitted,generally specified in kilo bits per second (kbit/s); and delay,comprising the time before which said user information must bedelivered, generally specified in milliseconds (ins). In addition to theforegoing, requirements can be placed on peak bandwidth andretransmission bandwidth as well. The peak bandwidth specifies a maximumnecessary resource reservation in case of variable bit rate streams.Retransmission bandwidth reservation specifies resource reservationnecessary for dealing with transmission errors

Four different traffic classes of applications have been defined in the3GPP technical specification (3GPP TS23.107v3.3.0, “QoS Concept andArchitecture,” http://www/3g_(D)p.org, June 2000):

-   -   1. Conversational class (e.g. voice)    -   2. Streaming class (e.g. streaming video)    -   3. Interactive class (e.g. web browsing)    -   4. Background class (e.g. background downloads of e-mail or        files)        These are listed with the conversational class having the most        stringent delay constraints and the background class having the        loosest or no requirement for delay. Correspondingly, various        QoS attributes are defined including maximum bit rate, maximum        Service Data Unit (SDU) size, residual bit error ratio, etc.        Traffic classes are not limited to the aforementioned. In fact,        there is no unique way of classification that is followed by all        standardization institutes. Broadly, however, one can define two        fundamentally different types of services: one that is time        critical and the other that is not (often referred to as        best-effort service).

In communication terms, being able to meet the aforementioned QoSrequirements translates into providing certain guarantees in terms ofaccess to the communications channel 200 and providing specific radioprotocol parameters. For a token based Ping-Pong protocol, wherepriority slots 360 provide the mechanism for regulating a guaranteedaccess to the channel 200, the relevant radio protocol parameters arepriority slot interval, priority slot phase, modulation format andpacket duration (dependent on the modulation format). These are assignedaccording to the above described QoS parameters.

Referring now to FIG. 4, there is provided a general block diagram of amapping function 475 for implementing the system and method of thepresent invention within a personal device 10. The mapping function 475has an input for receiving at least one of the QoS parameters includingbut not limited to the delay, maximum bit rate, maximum data unit size,and the average bit rate. The mapping will also take into account theusage of the channel by already established services.

The quality service parameters are mapped to various radio protocolparameters on a channel 200 including, but not limited to, at least oneof the priority slot interval, the priority slot phase, the packetduration and the modulation scheme. Using the mapping function 475 theQoS parameters may be easily mapped to the radio protocol parameters ofthe channel 200.

The manner in which one or more QoS parameters are mapped to one or moreradio protocol parameters by the mapping function 475 depends upon thetype of service utilized and on the current use of the channel by otherservices. The mapping of said QoS parameters to these radio protocolparameters must occur for single services in isolation, for multipleservices at the same time and for services requiring retransmissionbandwidth.

The mapping of quality of service requirements for a single timecritical service to radio control parameters on the radio channel 200using the mapping function 475 would occur in the following manner. Thepriority slot interval of a time critical service is derived from therequired delay QoS parameter of the time critical service. The priorityslots for a time critical service are assigned to occur on a periodicbasis. The priority slots are spaced such that all data may betransmitted before expiration of the required delay as shown in FIG. 5.Thus, the priority slot interval must be smaller than the delay.

Sensitivity to transmission errors of time critical services may becombated by transmitting the packets carrying the user information inrobust modulation formats. This comes at the expense of air interfacetime, as illustrated in FIGS. 6 a and 6 b. If an application exhibitserror resilience, this can be exploited by transmitting the packets 690using a dense modulation format (FIG. 6 a) resulting in a shortermaximum packet duration 695. This consumes less power and allowsmultiplexing of more services on to the radio channel 200 between thepackets 690. Thus, the error resistant application services illustratedin FIG. 6 a provide more space for additional traffic than thatillustrated in FIG. 6 b, wherein a less dense modulation format isrequired due to the application's lack of error resilience. It is notedthat the priority slot interval 680 is the same in each application, butadditional spaces are available between packets 690 in FIG. 6 a, due tothe shorter packet duration 695 arising from the dense modulationformat.

Non time critical applications allow a greater flexibility in schedulingtraffic. Non time critical services can be of two types, as illustratedin FIG. 7, having different QoS requirements, bandwidth demanding orbest effort. Bandwidth demanding services usually require only a singlequality of service parameter, namely average bandwidth expressed inbits/s. Since there is no particular periodicity in which the messagemust be generated, or a particular time limit before which the messagemust be delivered on a microscopic level, there is no notion of a framerate or maximum packet duration. Within this time frame, it is notimportant at exactly which time access occurs. But on average, withinsuch a time frame, the bandwidth should be attained. So this means thatthe bandwidth demanding services have no strict delay requirements in amicroscopic sense, but they do have some requirements in a macroscopicsense.

The maximum packet duration is only limited by the maximum packetduration allowed on the radio channel 200. Demands posed by bandwidthdemanding services can also be met using priority slots. While priorityslots offer the right to transmit, they also interrupt traffic. Sinceservices of this nature are not time critical, co-existence with otherservices will be enhanced by allocating longer packets. This allows thepriority slots interval to be larger and minimizes overhead.

Best effort services have no formal quality of service demands. However,these services rely on the “best effort” aspect of the protocol to getaccess to a channel. Typically, the packets may be sent using a densemodulation format in order to minimize the air-time occupancy. Whilesuch transmissions are most vulnerable to errors, multipleretransmissions may be performed. Typically, no priority slots arereserved to support this service. Due to the best effort nature of therequired quality of service, time is not a critical factor.

The retransmission bandwidth of non time critical but bandwidthdemanding services may require either the soft guarantee or a hardguarantee of data transmission as shown in FIGS. 8 a and 8 b. If a softguarantee is utilized (FIG. 8 a), capacity momentarily not used on thechannel, can be deployed for retransmissions. With soft guarantees, noguaranteed channel access for retransmissions is provided. The priorityinterval 800 between the assigned priority slots 802 can be maximized asit only considers the average bandwidth required assuming no errors.

Retransmission bandwidth may also be assured by hard guarantees (FIG. 8b). Hard guarantees assign more priority slots 802 to a particularservice in order to guarantee access to the channel for any necessaryretransmissions. By signing more priority timeslots 802 to a particularapplication, the application has more guaranteed opportunities toretransmit packets that may not have been correctly received. However,by using the hard guarantee format system, system throughput is affectedsince more channel resources are utilized by a single application. Thesituation may also arise when an application gains control via apriority slot but no retransmission of information is necessary. Thus, acertain amount of time is required to determine that no retransmissionis necessary and to release the priority slot to a next application.

Based upon the foregoing descriptions and with respect to the mapping oftime critical and non time critical services to radio parameters, wewill now consider transmitting multiple services simultaneously upon asingle radio channel. It should be understood that the number of timeslots illustrated within the priority intervals and slot durations areillustrative only and as a practical case there will be obtained manymore slots within the intervals. In general, multiple services demandingguaranteed access to the channel are supported by staggering thepriority slot intervals assigned to a particular service. This isachieved by choosing different phases (starting reference points) forthe train of priority slots belonging to services.

Referring now to FIG. 9, there are illustrated two time criticalservices 950 with identical quality of service requirements that aresharing a same radio channel 200. While a separate trace is shown foreach time critical service 950, it should be understood that theseservices are provided upon a same radio channel 200. The services maycomprise any type of time critical service. For simplicity, thedestination units are not shown in FIG. 9 or the subsequent figures.With respect to a reference point 955, the first time critical service950A gets a priority slot interval 960 with priority slot phase φ=0. Thepriority slot phase comprises the offset from between the priority slotsof the time critical service and the reference point 955. The referencepoint 955 is a common point in time in which all services participatingon this radio channel 200 are aware and use for a common reference pointand may be at any location. As can be seen in FIG. 9, time criticalservice 950A begins transmitting the data packet 965 at reference point955 and begins transmitting a next data packet 970 after expiration ofthe priority slot interval 960.

The second time critical service 950B has a same priority slot interval960 and obtains access to the radio channel 200 at a phase offset(different phase) 975 from the reference point 955. In thisillustration, the phase 975 for the second time critical service 950B isequal to half of the priority slot interval 960 of the first service950A. However, another phase offset 975 could also have been chosen. Thelower bound on the phase 975, i.e., the density of staggering, is set bythe maximum packet duration 980.

Time critical services can also co-exist by staggering priority slots asillustrated in FIG. 10. FIG. 10 illustrates a hypothetical scenariowherein a new time critical service 1090 with certain quality of servicerequirements is to be admitted in the midst of the time criticalservices 950 discussed with respect to FIG. 9. In this case, the delayrequirements of all of the three services are identical. The maximumpacket duration 1005 is indicated in the top row. The solution in thiscase is to plan a shorter priority slot interval 1010 for the timecritical service 1090 that can fit in between the priority slot interval960 of the two time critical services 950. The bottom trace shows onepossible mapping scenario for the time critical service 1090. In orderto guarantee that the longest message gets through, the priority slots1015 are assigned in such a way that if the largest packet is split intwo there is enough room to fit the longest message in between the twotime critical services packets of the radio channel 200. Because themessage length of some services may be variable and messages will besplit up, the resulting priority slot allocation will occasionallyresult in unused priority slots as shown at 1030. At 1030, priority slot1015 has obtained control of the radio channel 200, but no data isavailable to be transmitted. In this case, the service passes control toanother service.

So far, the multiplexing of time critical services has been described.The multiplexing is accomplished by proper assignment and positioning ofpriority slots. Now the inclusion of non time critical services will beconsidered. Since priority slots provide unconditional access to achannel 200, they inherently cause an interruption of traffic.Interruption of time-critical traffic by non time critical services isnot desirable. Accordingly, non time critical traffic should preferablenot be controlled by assigning priority slots. Best effort traffic canbe carried out using the ping pong mechanism between the time-criticaltraffic. Referring now to FIG. 11, there are illustrated three differentservices sharing the same radio channel 25. The services include a firsttime critical service 1150, an a second time critical service 1155 and abest effort non time critical service 1160. Priority slots 1162 andpacket duration 1165 of a first time critical service 1150 are shown inthe top trace 1150 a. The second trace 1150 b illustrates the priorityslot interval 1175 and the variable packet duration 1170 of the secondtime critical service 1155. The periods in between the time-criticaltransmissions can be used for supporting the best effort service 1160.Thus, it can be seen that each packet 1180 of the best effort service1160 is included in the openings between the packets of the timecritical services 1155 and 1150. The best effort service 1160 relies ona fair token distribution policy in order to gain access to the channel2000 and, thus, no priority slots are allocated.

Referring now to FIG. 12, non time critical services requiring bandwidthguarantees may use priority slots 1286. Since delay is not an issue, theconcept of delivering frames of bits before a certain time is not anissue. However, in order to minimize overhead, and cause minimuminterruptions, user information should be transmitted in largercontiguous blocks. The largest available block will generally bedetermined by appearance of the next priority slot (probably belongingto the time critical service that has the smallest delay requirements).The third trace of FIG. 12 illustrates a non-time-critical bandwidthdemanding service 1285. A much larger priority slot interval is used ascompared to the time critical services 1290. The size of the priorityslot interval 1295 is dependent upon the bandwidth requirement andmaximum packet size.

The priority slot intervals of the time critical services will bedifferent as illustrated in FIGS. 9-12. Such a situation inevitably willlead to a contention problem wherein a priority slot of another servicewill either occur while a packet transmission of the previous service isstill in progress, or may occur at the same time of another priorityslot. Contention problems can be resolved by allowing higher prioritytraffic to take precedence. Thus, in FIG. 13 the synchronous traffic 300takes precedence over the isochronous traffic 305, which takesprecedence over the bandwidth demanding asynchronous 310 which will takeprecedence over a best effort asynchronous traffic. In the case ofcontention between packets of equal traffic types, the contention mustbe resolved by granting the right to the owner of the leading priorityslot. A simple scheme might embody giving up the right to transmit inthe case of contention. If the priority slots coincide exactly, thecontention may be resolved by giving the service originating from thelowest address to take precedence.

Within the above-described system, required bandwidths can be providedby using a combination of maximum packet duration and the priority slotinterval. In order to support multiple services, the priority slotsbelonging to different services must be staggered. The priority slotphase can be used to achieve this staggering. Additionally, if there arerequirements on the delay, the priority slot interval along with thephase can be chosen in such a way as to meet these delay requirements.The delay places an upper bound on the priority slot interval. Losstolerance provided by the application can be exploited by transmittingpackets using a dense modulation format, which can under clean channelconditions allow admission of more services while allowing vulnerablepackets to be transmitted in more robust formats. Either the packetduration, or the priority slot interval can be negotiated in such a waythat a certain level of retransmission can be guaranteed for packetsoriginating from applications that are sensitive to errors. For multipleservices using the same channel, the overall mapping has to take intoaccount the QoS requirements of each individual service. If anadditional, new service is deployed, the current mapping of the existingservices may have to be altered in order to accommodate the new service.If one or more QoS requirements are endangered by the new service, thenew service may be denied (admission control) or it may have to relaxits QoS requirements.

The previous description is of a preferred embodiment for implementingthe invention, and the scope of the invention should not necessarily belimited by this description. The scope of the present invention isinstead defined by the following claims.

1. A method for transmitting, by a communications unit, packets of aservice having quality of service (QoS) requirements, comprising thesteps of receiving QoS parameters associated with a service including atleast one of delay, maximum bit rate, maximum data unit size and averagebit rate, mapping the QoS parameters to radio protocol parametersincluding at least one of a priority slot interval, a priority slotphase, a packet duration and modulation format for a radio channel; andtransmitting the packets on the radio channel according to the mappedradio protocol parameters.
 2. The method of claim 1, wherein the step ofmapping further comprises the steps of deriving the priority slotinterval for a time critical service from the delay of the time criticalservice
 3. The method of claim 2, wherein the step of mapping furtherincludes the step of setting the priority slot interval of the timecritical service less than the delay
 4. The method of claim 1, whereinthe step of mapping further includes the step of modulating the packetsresponsive to an error resilience of an associated application
 5. Themethod of claim 4, wherein the step of modulating further includes thestep of modulating the packets from error resilient applications using adense modulation format.
 6. The method of claim 1, wherein the step ofmapping further comprises the steps of setting a priority slot intervalsmaller than a required delay and larger than a maximum packet duration7. The method of claim 1, wherein the step of transmitting furthercomprises the step of including within at least one packet of thepackets a priority timeslot providing an application associated with thepacket exclusive control of the radio channel
 8. The method of claim 1,wherein the step of mapping further comprises the step of staggeringpriority slots of at least two time critical applications to preventtransmissions at a same time.
 9. The method of claim 8, wherein the stepof staggering further comprises the step of determining a priority slotphase for at least one time critical application
 10. The method of claim8, wherein the step of staggering, further comprises the step ofestablishing a first priority slot phase associated with a firstapplication that falls within a second priority slot interval associatedwith a second application wherein transmission of the packets of thefirst and second application substantially occur in different timeslotsof the radio channel
 11. The method of claim 1, wherein the step ofmapping further comprises the step of establishing a priority slotinterval of a first application having sufficient space to receive afirst portion of a largest packet associated with a second applicationin a first interval and a remaining portion of the largest packetassociated with the second application in a second interval.
 12. Themethod of claim 1, wherein the step of transmitting further comprisesthe step of transmitting packets associated with a non time criticalapplication between transmission of packets of time criticalapplications.
 13. The method of claim 1, wherein the step oftransmitting further comprises the steps of detecting a contentionbetween two packets attempting to control a radio channel at a sametime, determining an application associated with the packet, andproviding access to the radio channel to the packet associated with theapplication having a higher priority.
 14. The method of claim 1, whereinthe step of mapping further comprises the step of establishing apriority slot interval enabling retransmission of packets within asingle priority slot interval
 15. The method of claim 1, wherein thestep of mapping further comprises the step of establishing a priorityslot interval that provides multiple priority slots for retransmission16. A method for transmitting, by a communications unit, packets havingquality of service (QoS) requirements, comprising the steps of:receiving QoS parameters associated with a service including at leastone of delay, maximum bit rate, maximum data unit size and average bitrate, mapping the QoS parameters to radio protocol parameters includingat least one of a priority slot interval, a priority slot phase, apacket duration and modulation format for a radio channel; establishinga priority slot for at least a portion of the packets of the pluralityof packets, said priority slot providing exclusive control of the radiochannel to an associated application; and transmitting the packets onthe radio channel according to the mapped radio protocol parameters 17.The method of claim 16, wherein the step of mapping further comprisesthe steps of determining a priority slot interval and an offset to meeta quality of service delay requirement
 18. The method of claim 16,wherein the step of mapping further comprises the steps of deriving thepriority slot interval for a time critical service from the delay of thetime critical service.
 19. The method of claim 16, wherein the step ofmapping further comprises the step of staggering priority slots of atleast two time critical applications to prevent transmissions at a sametime.
 20. The method of claim 19, wherein the step of staggering furthercomprises the step of establishing a priority slot phase of a firstapplication having sufficient space to receive a first portion of alargest packet associated with a second application in a first intervaland a remaining portion of the largest packet associated with the secondapplication in a second interval.
 21. The method of claim 16, whereinthe step of transmitting further comprises the step of transmittingfirst packets associated with a non time critical application betweentransmission of packets of time critical applications.
 22. The method ofclaim 16, wherein the step of mapping further comprises the step ofestablishing a priority slot interval enabling retransmission of packetswithin a single priority slot interval.
 23. The method of claim 16,wherein the step of mapping further comprises the step of establishing apriority slot interval that provides multiple priority slots forretransmission.
 24. An apparatus for mapping quality of service (QoS)parameters of an application to radio control parameters of a radiochannel in a personal device, comprising the step of: an input forreceiving QoS parameters associated with a service including at leastone of delay, maximum bit rate, maximum data unit size and average bitrate; and logic for mapping the QoS parameters for a radio channel toradio protocol parameters including at least one of a priority slotinterval, a priority slot phase, a packet duration and modulationformat, and transmitting packets having the QoS requirements on theradio channel according to the mapped radio protocol parameters.
 25. Theapparatus of claim 24, wherein the logic further derives the priorityslot interval for a time critical service from the delay of the timecritical service.
 26. The apparatus of claim 25, wherein the logicfurther derives the priority slot interval of the time critical serviceless than to the delay.
 27. The apparatus of claim 24, wherein the logicfurther modulates the packets responsive to an error resilience of anassociated application
 28. The apparatus of claim 24, wherein the logicfurther sets a priority slot interval smaller than a required delay andlarger than a maximum packet duration
 29. The apparatus of claim 24,wherein the logic further includes within at least one packet of thepackets a priority timeslot providing an application associated with thepacket exclusive control of the radio channel.
 30. The apparatus ofclaim 24, wherein the logic staggers priority slots time criticalapplications of at least two to prevent transmissions at a same time.31. The apparatus of claim 26, wherein the logic further establishes afirst priority slot interval associated with a first application thatfalls within a second priority slot phase associated with a secondapplication wherein transmission of the packets of the first and secondapplication substantially occur in different timeslots of the radiochannel.
 32. The apparatus of claim 24, wherein the logic furtherestablishes a priority slot interval of a first application havingsufficient space to receive a first portion of a largest packetassociated with a second application in a first interval and a remainingportion of the largest packet associated with the second application ina second interval
 33. The apparatus of claim 24, wherein the logicfurther transmits first packets associated with a non time criticalapplication between transmission of packets of time criticalapplications.
 34. The apparatus of claim 24, wherein the logic furtherdetects a contention between two packets attempting to control a radiochannel at a same time, determines an application associated with thepacket, and provides access to the radio channel to the packetassociated with the application having a higher priority.